I'm trying to identify a Sci-Fi (short I think) story that I read many years ago, probably in the 80's.
The core of the story was that an astronaut is stranded around a planet in a stationary orbit. He manages to make contact with the inhabitants but can only speak with them for a short time before the planet circles round and he loses contact. When the inhabitants come back into range again they have evolved exponentially and this cycle continues for several iterations until they eventually save his life. I can't remember exactly how but I seem to recall that it involves the physical moving of a planet or sun that was what he was at risk from.
Does anyone know what this is?